Revealing mistake: During the scene in which the Doctor is climbing the transmitter, there is a shot in which he is viewed from above and is then struck by lightning. In this shot, the Doctor's foot disappears briefly as it leaves the green screen on the ground under the actor. (00:38:25)
Continuity mistake: When Izzie is looking at the patient board, there are some lines on it which have been wiped out. But in the next scene we actually see Meredith walk to the board and wipe these exact same lines off (even though they were previously rubbed out...) (00:34:05)
Visible crew/equipment: After Hank Dale tells Steve Pinkus that he wants to know "How it feels to get away with murder," Hank throws a punch, and in the next wide shot we can see the second cameraman's arms holding an additional camera, presumably to film the close-up, at the right side of the screen. (00:32:35)
Visible crew/equipment: During the scene where Dennis and the Waitress, Mac and Dee successively walk into the back office to talk to Charlie near the beginning of the episode, in some of the shots, you can see outside the office door, and you can see the top of the set has no ceiling, and even see part of a stage-light.
Continuity mistake: When Charlie is in his office talking to Larry, while going over the potential killers and victims, he writes the word "Killers" on the board and circles it. Then, when Charlie notices that Larry has left and says "gone", the writing is different. The 'k' is wider, and most noticeably, the left side of the circle is gone, and the loop in his 's' disappears. Once Charlie goes back to working, the word changes back to how it was originally written. (00:38:20)
Continuity mistake: When the bus driver finds Roger, the Dignity Towers Retirement Home bus is only a few feet away from them. But in the shot where Roger says "How do I get home? How do I get home?", there was no sign of any bus for many many meters. As if the bus just appeared out of nowhere. (00:09:45)
Continuity mistake: When Katara is trying to heal the wounded earthbender, she gives Sokka the idea to take down The Drill from the inside. Sokka then stops her from saying anything while she is sitting down, and she is wearing her necklace. When she stands up in that same shot, the necklace is gone, like they forgot to animate it. (00:07:35)